360=x^2+2x^2-30

Solution for 360=x^2+2x^2-30 equation:

360=x^2+2x^2-30

We move all terms to the left:

360-(x^2+2x^2-30)=0

We get rid of parentheses

-x^2-2x^2+30+360=0

We add all the numbers together, and all the variables

-3x^2+390=0

a = -3; b = 0; c = +390;
Δ = b2-4ac
Δ = 02-4·(-3)·390
Δ = 4680
The delta value is higher than zero, so the equation has two solutions
We use following formulas to calculate our solutions:
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}$

The end solution:

$\sqrt{\Delta}=\sqrt{4680}=\sqrt{36*130}=\sqrt{36}*\sqrt{130}=6\sqrt{130}$
$x_{1}=\frac{-b-\sqrt{\Delta}}{2a}=\frac{-(0)-6\sqrt{130}}{2*-3}=\frac{0-6\sqrt{130}}{-6}
=-\frac{6\sqrt{130}}{-6}
=-\frac{\sqrt{130}}{-1}
$
$x_{2}=\frac{-b+\sqrt{\Delta}}{2a}=\frac{-(0)+6\sqrt{130}}{2*-3}=\frac{0+6\sqrt{130}}{-6}
=\frac{6\sqrt{130}}{-6}
=\frac{\sqrt{130}}{-1}
$